Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
A developer is building a mobile application that uses Amazon Cognito for user authentication. After a user signs in, the application needs to access an Amazon DynamoDB table. The developer has set up an identity pool with an authenticated role. The IAM role attached to the authenticated identity has a policy allowing the required DynamoDB actions. However, users report that they cannot perform DynamoDB operations. What is the MOST likely cause of this issue?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
The identity pool is not configured to use the authenticated role.
If the identity pool were not configured, the app would likely fail to obtain any credentials entirely, but the question states the developer set up the identity pool with an authenticated role, so this is not the most likely cause.
B
Distractor review
The app is not passing the correct identity ID.
The identity ID is assigned by Cognito; the AWS SDK automatically handles this. Passing an incorrect ID would cause authentication failures, but the scenario describes users signed in and still unable to perform operations.
C
Best answer
The IAM role's trust policy does not allow Cognito to assume it.
The trust policy of the IAM role must grant the Cognito Identity service principal the sts:AssumeRole permission. Without it, Cognito cannot issue credentials, resulting in denied actions.
D
Distractor review
The DynamoDB table is encrypted with a different KMS key.
If encryption with a customer-managed KMS key is used, the role would also need kms:Decrypt permissions, but the most likely initial cause is the trust policy issue.
Common exam trap
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Technical deep dive
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Related practice questions
Related DVA-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A developer is building a REST API using Amazon API Gateway that will serve static content from an Amazon S3 bucket. The API should cache responses for frequently accessed objects to reduce latency. Which API Gateway feature should the developer enable?
Question 2
A developer is running a web application on multiple Amazon EC2 instances behind an Application Load Balancer (ALB). The application needs to store user session state that must be available across all instances. The session data is small and temporary but must survive individual instance failures. Which AWS service should the developer use to store this session state?
Question 3
A developer has an AWS Lambda function that processes messages from an Amazon SQS standard queue. The function is idempotent and currently has a batch size of 10. The developer wants to increase throughput and increases the batch size to 100. After the change, CloudWatch metrics show a significant increase in throttles and the queue backlog is growing. The function's reserved concurrency is set to 10. What is the most effective action to resolve the throttling and improve throughput?
Question 4
A developer is managing an application running on Amazon EC2 instances behind an Application Load Balancer. Users report that the application becomes unresponsive after several hours, and restarting the instance temporarily fixes the issue. The developer suspects a memory leak but cannot add custom instrumentation. Which AWS service can collect memory utilization metrics and help identify the memory leak with minimal configuration?
Question 5
A developer is building a serverless web application using AWS Lambda and Amazon DynamoDB. The application needs to perform complex aggregations on data stored in DynamoDB. Which AWS service should the developer use to perform these aggregations efficiently without reading all the data into Lambda?
Question 6
A developer has an Amazon S3 bucket containing private user documents. The application must generate a time-limited URL for users to download their own documents without requiring the users to have AWS credentials. Which solution should the developer use?
FAQ
Questions learners often ask
What does this DVA-C02 question test?
Read the scenario before looking for a memorised answer.
What is the correct answer to this question?
The correct answer is: The IAM role's trust policy does not allow Cognito to assume it. — For Cognito Identity Pools to grant permissions to authenticated users, the IAM role's trust policy must allow the Cognito Identity service to assume it. Without the proper trust relationship, Cognito cannot obtain temporary credentials for the user, even if the permissions policy is correct. The identity ID passed by the app is typically handled automatically by the SDK. If the identity pool is configured, the role is used by default. KMS key encryption would cause a different error (AccessDenied) but is less common.
What should I do if I get this DVA-C02 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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